Who knows the water formula since school time? Of course that's all. It is likely that out of the entire chemistry course, many who do not later study it specializedly only have knowledge of what the H 2 O formula means. But now we will try to figure out as much as possible and deeply what water is? What are its main properties and why it is impossible to live on planet Earth without it.
Water as a substance
The water molecule, as we know, consists of one oxygen atom and two hydrogen atoms. Its formula is written as follows: H 2 O. This substance can have three states: solid - in the form of ice, gaseous - in the form of steam, and liquid - as a substance without color, taste and smell. By the way, this is the only substance on the planet that can exist in all three states simultaneously in natural conditions. For example: at the poles of the Earth - ice, in the oceans - water, and evaporation under the sun's rays is steam. In this sense, water is abnormal.
Still water is the most abundant substance on our planet. It covers the surface of planet Earth by almost seventy percent - these are the oceans, and numerous rivers with lakes, and glaciers. Most of the water on the planet is salty. It is unsuitable for drinking and for farming. Fresh water makes up only two and a half percent of the total amount of water on the planet.
Water is a very strong and high-quality solvent. Due to this, chemical reactions in water take place at a tremendous speed. This same property affects the metabolism in the human body. It is a well-known fact that the body of an adult is seventy percent composed of water. In a child, this percentage is even higher. By old age, this figure drops from seventy to sixty percent. By the way, this feature of water clearly demonstrates that it is precisely the basis of human life. The more water in the body - the healthier, more active and younger it is. Therefore, scientists and doctors of all countries tirelessly insist that you need to drink a lot. It is pure water, and not substitutes in the form of tea, coffee or other drinks.
Water forms a climate on the planet, and this is not an exaggeration. Warm currents in the ocean heat entire continents. This is due to the fact that water absorbs a lot of solar heat, and then gives it away when it starts to cool. So it regulates the temperature on the planet. Many scientists say that the Earth would have cooled down long ago and become a stone, if not for the presence of such an amount of water on a green planet.
Water properties
Water has many very interesting properties.
For example, water is the most mobile substance after air. From the school course, many probably remember such a thing as the water cycle in nature. For example: a trickle evaporates under the influence of direct sunlight, turns into water vapor. Further, this steam is transported somewhere through the wind, collected in clouds, or even thunderclouds, and falls in the mountains in the form of snow, hail or rain. Further, from the mountains the brook runs down again, partially evaporating. And so - in a circle - the cycle repeats millions of times.
Also, water has a very high heat capacity. It is because of this that water bodies, especially oceans, cool very slowly during the transition from the warm season or time of day to the cold. Conversely, when the air temperature rises, the water heats up very slowly. Due to this, as mentioned above, water stabilizes the temperature of the air on our planet.
After mercury, water has the highest surface tension. It is impossible not to notice that a drop accidentally spilled on a flat surface sometimes becomes an impressive speck. This shows the viscosity of water. Another property is manifested in her when the temperature drops to four degrees. As soon as the water cools to this mark, it becomes lighter. Therefore, ice always floats on the surface of the water and freezes with a crust, covering itself with rivers and lakes. Due to this, in ponds freezing in winter, fish does not freeze.
Water as a conductor of electricity
First, you should find out what electrical conductivity is (including water). Conductivity is the ability of a substance to conduct an electric current through itself. Accordingly, the electrical conductivity of water is the ability of water to conduct current. This ability directly depends on the amount of salts and other impurities in the liquid. For example, the electrical conductivity of distilled water is almost minimized due to the fact that such water is purified from various additives that are so needed for good electrical conductivity. An excellent conductor of current is sea water, where the concentration of salts is very high. Conductivity also depends on the temperature of the water. The higher the temperature, the greater the conductivity of the water. This pattern was revealed thanks to the many experiments of physicists.
Water conductivity measurement
There is such a term - conductometry. So called one of the methods of electrochemical analysis based on the electrical conductivity of solutions. This method is used to determine the concentration in solutions of salts or acids, as well as to control the composition of some industrial solutions. Water has amphoteric properties. That is, depending on the conditions, it is capable of exhibiting both acidic and basic properties — acting both as an acid and as a base.
The device used for this analysis has a very similar name - a conductometer. Using a conductivity meter, the electrical conductivity of electrolytes in solution is being analyzed and is being analyzed. Perhaps it is worth explaining another term - electrolyte. This is a substance that, when dissolved or melted, decomposes into ions, due to which an electric current is subsequently conducted. An ion is an electrically charged particle. Actually, the conductometer, taking as a basis certain units of the electrical conductivity of water, determines its specific conductivity. That is, it determines the electrical conductivity of a specific volume of water, taken as the initial unit.
Even before the beginning of the seventies of the last century, the unit of measurement “mo” was used to indicate the conductivity of electricity, it was a derivative of another quantity - Ohm, which is the main unit of resistance. Electrical conductivity is a value inversely proportional to resistance. Now it is measured in Siemens. This value got its name in honor of the physicist from Germany - Werner von Siemens.
Siemens
Siemens (can be designated as Cm, and S) - this is the reciprocal of Ohm, which is a unit of measurement of electrical conductivity. One cm is equal to the electrical conductivity of any conductor whose resistance is 1 ohm. Siemens is expressed through the formula:
- 1 cm = 1: Ohm = A: B = kg −1 · m −2 · s³A², where
A is ampere
In - volt.
Thermal conductivity of water
Now let's talk about what is thermal conductivity. Thermal conductivity is the ability of a substance to transfer thermal energy. The essence of the phenomenon is that the kinetic energy of atoms and molecules, which determine the temperature of a given body or substance, is transferred to another body or substance during their interaction. In other words, thermal conductivity is the heat exchange between bodies, substances, and also between a body and a substance.
The thermal conductivity of the water is also very high. People daily use this property of water without noticing it. For example, pouring cold water into a container and cooling it with drinks or products. Cold water takes away heat from the bottle, container, giving away cold in return, and a reverse reaction is possible.
Now this same phenomenon can easily be imagined on a planetary scale. The ocean heats up during the summer, and then - with the onset of cold weather, slowly cools down and gives its heat to the air, thereby heating the continents. Cooling over the winter, the ocean begins to warm up very slowly compared to the earth and gives its coolness to the continents languishing from the summer sun.
Density of water
It was described above that fish lives in the pond in winter due to the fact that the water freezes with a crust over their entire surface. We know that water begins to turn into ice at a temperature of zero degrees. Due to the fact that the density of water is greater than the density of ice, ice floats and hardens on the surface.
What are the redox properties of water
Also, water under different conditions can be both an oxidizing agent and a reducing agent. That is, water, giving its electrons, is positively charged and oxidized. Or it acquires electrons and charges negatively, which means it is restored. In the first case, water is oxidized and is called dead. It has very powerful bactericidal properties, but you don’t need to drink it. In the second case, the water is live. It invigorates, stimulates the body to recover, carries energy to the cells. The difference between these two properties of water is expressed in the term “redox potential”.
What water can react to
Water is able to react with almost all substances that exist on Earth. The only thing that for the occurrence of these reactions is to provide a suitable temperature and microclimate.
For example, at room temperature, water perfectly reacts with metals such as sodium, potassium, barium - they are called active. With halogens - this is fluorine, chlorine. When heated, water perfectly reacts with iron, magnesium, coal, methane.
Using various catalysts, water reacts with amides, esters of carboxylic acids. The catalyst is a substance, as if pushing the components to a mutual reaction, accelerating it.
Is there water anywhere else besides the earth?
So far, on no planet of the solar system, except Earth, has water been detected. Yes, they suggest its presence on satellites of such giant planets as Jupiter, Saturn, Neptune and Uranus, but so far scientists have no exact data. There is another hypothesis, not yet fully verified, about groundwater on the planet Mars and on the Earth’s satellite - the Moon. Regarding Mars, a number of theories have been put forward that there once was an ocean on this planet, and its possible model was even designed by scientists.
Outside the solar system, there are many large and small planets, where, according to scientists, there may be water. But so far there is not the slightest opportunity to verify this for sure.
How to use the thermal and electrical conductivity of water for practical purposes
Due to the fact that water has a high heat capacity, it is used in heating pipelines as a heat carrier. It provides heat transfer from producer to consumer. As an excellent coolant, water is used by many nuclear power plants.
In medicine, ice is used for cooling, and steam is used for disinfection. Ice is also used in the catering system.
In many nuclear reactors, water is used as a moderator for the success of a nuclear chain reaction.
Water under pressure is used for cracking, breaking, and even for cutting rocks. It is actively used in the construction of tunnels, underground premises, warehouses, subways.
Conclusion
From the article it follows that water in its properties and functions is the most irreplaceable and amazing substance on Earth. Does the life of man or any other living creature on Earth depend on water? Of course, yes. Does this substance contribute to the conduct of scientific activity by man? Yes. Does water have electrical conductivity, thermal conductivity and other beneficial properties? The answer is yes too. Another thing is that the water on Earth, and even more so clean water, is less and less. And our task is to save and secure it (and, therefore, all of us) from extinction.